Greater Mekong Region Research Articles

Threats of dams to the persistence of the world's freshwater fishes

AbstractHabitat fragmentation due to dams is a well‐known threat to freshwater fish. Yet, the global consequences of fragmentation for the viability of freshwater fish populations are unknown. Here, we provide the first global assessment of the threats of dams to the persistence of freshwater fish species. We developed a global macroecological relationship between freshwater fish range size and body size and used this relationship to assess whether isolated range fragments are too small to support a species. Our assessment includes 7369 freshwater fish species and considers the effects of 31,780 dams globally. Furthermore, we performed a more detailed analysis of the threats of dams in Brazil, the greater Mekong region and the United States, using complementary national and regional data sets. Globally, more than half of the species analysed face extirpation in a part of their geographic range, with an average potential range loss of 3.3% (95%‐range: 0%–31.8%) across all species analysed. For 74 fish species, occurring in Brazil, China, India, the Mekong basin, the United States, South‐Africa and the East Adriatic Coast, more than 50% of their range is potentially lost. This includes 18 species threatened with extinction across their whole range. Our complementary regional analysis revealed that the potentially lost range increases by a factor of 2–4 when considering both large and small dams compared with considering only large dams (≥15 m), highlighting the need to establish more comprehensive global dam inventories. Our novel approach and global analysis identifies species at risk of extirpation as well as geographic hotspots of extirpation threat by dams, which can aid in establishing more effective strategies for global hydropower development and barrier removal efforts to optimise the trade‐offs between biodiversity conservation and the socio‐economic benefits of dams.

River reach types as large-scale biodiversity proxies for management: The case of the Greater Mekong Region

Large-scale development projects such as hydropower dams in the Greater Mekong Region (GMR) exert high pressure on freshwater resources. Environmental impact assessments in the region can help to understand the possible impacts of these projects, yet these assessments typically require biodiversity data that can be both costly and time-intensive to acquire. As a substitute, researchers often assume that river or ecosystem classes based on geophysical characteristics can be used as biodiversity proxies in large-scale assessments to account for a lack of biodiversity data. However, only limited research exists that compares the spatial distribution of river classes and fish species, and therefore it remains unclear how well river classes can represent fish assemblages or, more generally, biodiversity. To address this question, we here compared a new river reach classification, which used regional expert knowledge to build the classes, with a dataset of fish species distribution in the GMR. We conducted a Redundancy Analysis to estimate how much variability in the fish species data can be explained by the river reach types. The results show a moderate correlation between the datasets (adjusted R2 of 0.44). Based on these findings, we elaborate on the role of spatial hierarchy in fish species distribution and discuss possible implications for management and policies in the GMR.

Quantifying the illegal high-value rosewood trade and criminal trade networks in the Greater Mekong Region

Illegal trade network patterns may be explained by geographic, economic and environmental factors, and may change over time. Rosewood is one of the most valuable taxa in the illegal and unregulated wildlife trade, and we focus on its trade in the Greater Mekong Region. Using media sourced seizure data, we firstly present an empirical depiction of the confiscations of rosewood throughout Thailand over a seven-year period (2013–2019) based on 2274 seizure reports; mapping geographic locations, trends over time, transport route within Thailand and import and export into other Greater Mekong Region countries. We test factors explaining seizure patterns using a Generalised Linear Model and conducted basic analysis on suspect data using suspect nationality. We find that geographically timber crimes occur throughout Thailand, but especially in border areas with Cambodia and Laos; the final destination in most cases appears to be China. Suspects are backed by complex criminal networks. Geographic factors were the strongest in determining hotspots of seizure activity suggesting timber trafficking occurred mostly in border provinces. Our findings provide general support for the argument that rosewood trade network is transnational in terms of sourcing and consumption as well as actors involved. It raises important questions about crimes against the environment and the importance of domestic legalisation and how international regulations are effective in the protection of rosewood species. More generally, our study illustrates the ways online sourced seizure data can be used to provide an initial quantitative assessment of the rosewood trade network patterns.

Childhood encephalitis in the Greater Mekong region: critical to public health policy

Childhood encephalitis in the Greater Mekong region: critical to public health policy

Childhood encephalitis in the Greater Mekong region (the SouthEast Asia Encephalitis Project): a multicentre prospective study

SummaryBackgroundEncephalitis is a worldwide public health issue, with a substantially high burden among children in southeast Asia. We aimed to determine the causes of encephalitis in children admitted to hospitals across the Greater Mekong region by implementing a comprehensive state-of-the-art diagnostic procedure harmonised across all centres, and identifying clinical characteristics related to patients’ conditions.MethodsIn this multicentre, observational, prospective study of childhood encephalitis, four referral hospitals in Cambodia, Vietnam, Laos, and Myanmar recruited children (aged 28 days to 16 years) who presented with altered mental status lasting more than 24 h and two of the following minor criteria: fever (within the 72 h before or after presentation), one or more generalised or partial seizures (excluding febrile seizures), a new-onset focal neurological deficit, cerebrospinal fluid (CSF) white blood cell count of 5 per mL or higher, or brain imaging (CT or MRI) suggestive of lesions of encephalitis. Comprehensive diagnostic procedures were harmonised across all centres, with first-line testing was done on samples taken at inclusion and results delivered within 24 h of inclusion for main treatable causes of disease and second-line testing was done thereafter for mostly non-treatable causes. An independent expert medical panel reviewed the charts and attribution of causes of all the included children. Using multivariate analyses, we assessed risk factors associated with unfavourable outcomes (ie, severe neurological sequelae and death) at discharge using data from baseline and day 2 after inclusion. This study is registered with ClinicalTrials.gov, NCT04089436, and is now complete.FindingsBetween July 28, 2014, and Dec 31, 2017, 664 children with encephalitis were enrolled. Median age was 4·3 years (1·8–8·8), 295 (44%) children were female, and 369 (56%) were male. A confirmed or probable cause of encephalitis was identified in 425 (64%) patients: 216 (33%) of 664 cases were due to Japanese encephalitis virus, 27 (4%) were due to dengue virus, 26 (4%) were due to influenza virus, 24 (4%) were due to herpes simplex virus 1, 18 (3%) were due to Mycobacterium tuberculosis, 17 (3%) were due to Streptococcus pneumoniae, 17 (3%) were due to enterovirus A71, 74 (9%) were due to other pathogens, and six (1%) were due to autoimmune encephalitis. Diagnosis was made within 24 h of admission to hospital for 83 (13%) of 664 children. 119 (18%) children had treatable conditions and 276 (42%) had conditions that could have been preventable by vaccination. At time of discharge, 153 (23%) of 664 children had severe neurological sequelae and 83 (13%) had died. In multivariate analyses, risk factors for unfavourable outcome were diagnosis of M tuberculosis infection upon admission (odds ratio 3·23 [95% CI 1·04–10·03]), coma on day 2 (2·90 [1·78–4·72]), supplementary oxygen requirement (1·89 [1·25–2·86]), and more than 1 week duration between symptom onset and admission to hospital (3·03 [1·68–5·48]). At 1 year after inclusion, of 432 children who were discharged alive from hospital with follow-up data, 24 (5%) had died, 129 (30%) had neurological sequelae, and 279 (65%) had completely recovered.InterpretationIn southeast Asia, most causes of childhood encephalitis are either preventable or treatable, with Japanese encephalitis virus being the most common cause. We provide crucial information that could guide public health policy to improve diagnostic, vaccination, and early therapeutic guidelines on childhood encephalitis in the Greater Mekong region.FundingInstitut Pasteur, Institut Pasteur International Network, Fondation Merieux, Aviesan Sud, INSERM, Wellcome Trust, Institut de Recherche pour le Développement (IRD), and Fondation Total.

Lao PDR’s Perceptions and Strategies toward China’s Belt and Road Initiative

The purpose of this article is to clarify Laos’ perceptions and strategies toward China’s Belt and Road Initiative (BRI). The article argues that China’s growing influence over Southeast Asia, including Laos, and Laos’ increasingly urgent need for investment and improvement for its weak infrastructure have propelled Laos to become the most receptive country in Southeast Asia to support China’s BRI. Besides, Laos is the only landlocked country in the heart of the Greater Mekong region. Futhermore, the country still remains one of the poorest in Southeast Asia, and in one the world’s least developed countries. Therefore, the Lao government aims to transistion from a “landlocked” to a “land-linked” country. An improved highway network would move the country one step closer to achieving its landlinked strategy. Thus, Laos sees China’s BRI as a significant tool to promote its landlinked strategy. Accordingly, the Lao government’s welcoming attitude towards China’s BRI. As a result, China so far is the largest investor and aid donor on the country and has provided numberous development aid and invested in major infrastructure insighful views to better understand the current China’s BRI strategy in Southeast Asia and regional countries’ response to this initiative.

Crop-livestock integration provides opportunities to mitigate environmental trade-offs in transitioning smallholder agricultural systems of the Greater Mekong Subregion

CONTEXTThe Greater Mekong Subregion has been undergoing rapid agricultural transformation over the last decades, as traditional diverse subsistence-oriented agriculture is evolving towards intensified commercial production systems. Negative environmental impacts often include deforestation, nutrient pollution, and greenhouse gas (GHG) emissions. OBJECTIVEThis study aims to explore the potential of crop-livestock integration to mitigate trade-offs between economic and environmental impacts of smallholder farming systems at different stages of agricultural transition and degrees of agricultural diversity across the Greater Mekong Subregion. METHODSWe chose a ‘middle ground’ between detailed modeling of few, representative farming systems and modeling of large household populations. 24 low and high diversity farms were selected in Laos (Xieng Khouang province), Cambodia (Ratanakiri province) and Vietnam (Central Highlands) from a survey dataset of 1300 households. These farming systems were simulated with the whole-farm bio-economic and multi-objective optimization model FarmDESIGN, calculating operating profit, GHG emissions and nitrogen (N) balance. Two optimizations (‘business as usual’ vs. ‘crop-livestock integration’) were performed, generating ‘solution spaces’ or alternative configurations aiming to maximize profitability, keep farm N balanced and minimize GHG emissions. RESULTS AND CONCLUSIONSAgricultural systems across the sites differed in their production orientation and management practices, representing various stages of agricultural transition. Nitrogen balances varied between sites, being negative in Ratanakiri (average − 20.5 kg N ha−1 y−1) and Xieng Khouang (−36.5 kg N ha−1 y−1) and positive in the Central Highlands (73 kg N ha−1 y−1). Negative balances point to unsustainable mining of nutrients due to sale of cash crops without sufficient inputs, and positive balances to the risk of environmental contamination. Total GHG emissions ranged from 0.52–8.12 t CO2e ha−1 and were not significantly impacted by stage of agricultural transformation or agricultural diversity. GHG sources in Ratanakiri and Xieng Khouang were determined by crop residue burning while in Central Highlands fertilizer and livestock were main emitters. High diversity farms obtained higher operating profits (10,379 USD y−1) than low diversity farms (4584 USD y−1). Crop-livestock integration, a combination of measures including introduction of improved forages grasses, manure recycling and residue feeding, and reduction of residue burning, resulted in larger ‘solution spaces’, thus providing farmers with more options to mitigate agro-environmental trade-offs. SIGNIFICANCEThese findings underline the potential of crop-livestock integration to support sustainable intensification pathways in the Greater Mekong region. Public and private investment in further research and extension is needed to develop and scale context-specific crop-livestock integration practices.

Falling price induced diversification strategies and rural inequality: Evidence of smallholder rubber farmers

• This study uses a panel data of smallholder rubber farmers in Upper Mekong Region. • Smallholders tend to adopt diversification strategy in response to rubber price declines. • More dependence on rubber results in lower livelihood diversification. • Diversification strategy contributes to improving income and reducing rural inequality. While the expansions of natural rubber in the greater Mekong region from the 1990s were ambitious, the persistently low commodity price of rubber from 2012 makes smallholder rubber farmers suffer from vulnerable livelihoods. This study sheds light on the adjustments in livelihood strategies of smallholder rubber farmers when the upsurge in rubber prices came to an end. Based on the two-wave panel data from some 600 smallholder rubber farmers in the upper Mekong region, Southern Yunnan province of China, this study shows the diversification strategies of smallholders in response to falling rubber prices and examines the impacts of livelihood diversification strategies on farmer income and rural inequality. The results suggest that smallholder rubber farmers tend to shift family labor from farms to off-farm employment and diversify their livelihoods in the context of declining rubber prices. Notably, farmers with relatively low dependence on rubber are more likely to diversify their livelihoods. The falling price induced diversification strategy makes smallholders more resilient against future risks and narrows the rural income gap. The findings of this study advance the literature by providing evidence on how farmers' livelihood strategy and rural inequality change in the face of periodical rubber price volatility.

A framework for assessing the value of seasonal climate forecasting in key agricultural decisions

While climate information services are widely available, translating climate information into actionable solutions to reduce climate risk, which are readily taken up by producers, remains a critical challenge. Here, we apply a bio-economic approach to assess the potential economic value of seasonal climate forecasts (SCFs) as a basis for climate services for use in agricultural decision-making. We use a case study approach, quantifying the impacts of seasonal precipitation on rice cropping, a dominant farming system in the Greater Mekong Region (GMR) in Southeast Asia. We demonstrate values of seasonal precipitation forecasts for a range of forecast skill levels from low to perfect skill for three seasonal precipitation conditions (wet, normal and dry), as well as extreme conditions (extreme wet and extreme dry). Based on our integrated bio-economic assessment and seasonal variation in precipitation, we identify an optimal rice sowing window, which potentially results in improved yield and economic benefits compared with the currently applied sowing window. Applying this approach using common rice varieties grown by farmers – specifically, the medium growth duration Jasmine rice and the short duration Vietnamese long grain white rice variety OM 5451 – we find significant value in using seasonal precipitation forecasts to identify optimal sowing windows, ranging from an average of $135 ha−1 for precipitation forecasts at the current level (70% accuracy) of forecast skill to $220 ha−1 for perfect (100% accurate) precipitation forecasts.We propose that such a framework can be used to examine the value of using seasonal climate forecasts, even at current skill levels, in farm adaptive operational decision-making. We envisage that demonstration of the value of using seasonal forecasts in crop production system decisions will build user confidence and help in upscaling the use of climate information in the region and more broadly.

Streamflow prediction in “geopolitically ungauged” basins using satellite observations and regionalization at subcontinental scale

A novel approach of combining regionalization and satellite observations of various hydrological variables were employed to significantly improve prediction of streamflow signatures at “geopolitically ungauged” basins. Using the proposed step-wise physiography and climate-based regionalization approach, the model performance at ungauged basins reached 80% of performance of locally calibrated parameters and significantly outperformed the global regionalization parameters. The proposed water level based flow correlation was found to help diagnose models and outperform the existing performance metrics of simulated water levels at ungauged basins. The study also set up the first multi-national, multi-catchment hydrological model in the Greater Mekong region, the top global biodiversity and major disaster risk hotspot in the world through sequential and iterative refinement of the existing global hydrological model. New model setup or existing models in the poorly-gauged and ungauged basins could benefit from the proposed approach to predict and evaluate models at ungauged basins.

Linking Earth Observations for Assessing the Food Security Situation in Vietnam: A Landscape Approach

Land cover change and its impact on food security is a topic that has major implications for development in population-dense Southeast Asia. The main drivers of forest loss include the expansion of agriculture and plantation estates, growth of urban centers, extraction of natural resources, and water infrastructure development. The design and implementation of appropriate land use policies requires accurate and timely information on land cover dynamics to account for potential political, economical, and agricultural consequences. Therefore, SERVIR-Mekong led the collaborative development of a Regional Land Cover Monitoring System (RLCMS) with key regional stakeholders across the greater Mekong region. Through this effort, a modular system was used to create yearly land cover maps for the period 1988 - 2017. In this study, we compared this 30-year land cover time-series with Viet Nam national forest resources and agricultural productivity statistics. We used remote sensing-derived land cover products to quantify landscape changes and linked those with food availability, one of food security dimension, from a landscape approach perspective. We found that agricultural production has soared while the coverage of agricultural areas has remained relatively stable. Land cover change dynamics coincide with important legislation regarding environmental management and sustainable development strategies in Viet Nam. Our findings indicate that Vietnam has made major steps towards improving its' food security. We demonstrate that RLCMS is a valuable tool for evaluating the relationship between policies and their impacts on food security, ecosystem services and natural capital.

The Trafficking of Children in the Greater Mekong Region: A Review of Recent Literature

This review focuses on the literature on child trafficking in the Greater Mekong Region (GMR) in the last decade, as an update to Rafferty's (2007) review. The research is primarily organised into several main themes: public health implications, the trafficking of boys, cross‐border trafficking, the changing context and venues in which trafficking occurs, and trafficking in lesser‐studied regions of the GMR. The research reveals that children who are trafficked experience physical symptoms of abuse, sexually transmitted infections, mental health sequelae and substance abuse. Emerging research on the trafficking of boys elucidates relevant cultural issues, describing exploitation in street‐based and establishment‐based venues. Recent work describing children who are exploited in the Thai‐Cambodian border region reveals economic depression as a driver for migration into the area and high rates of violence. The literature also describes a shift in trafficking venues in Cambodia from brothels to entertainment venues. Much of the research to date has been conducted in Cambodia, Vietnam and Thailand, and there is preliminary research from the Lao People's Democratic Republic, but much remains unknown about trafficking in other GMR countries. Further research is required to identify the interactions of trafficked children in the GMR with healthcare settings, and, more specifically, to understand the medical implications of trafficking.‘This review focuses on the literature on child trafficking in the Greater Mekong Region in the last decade, as an update to Rafferty's (2007) review’Key Practitioner Messages Children trafficked in the GMR experience health consequences as a result of exploitation. Venues for trafficking in the GMR are shifting from brothels to off‐site and entertainment venues as a consequence of governments and local authorities increasing legal enforcement. Boys in the GMR are vulnerable to trafficking. Children who migrate for work in the GMR are vulnerable to trafficking. A trauma‐informed approach and a heightened level of awareness for a history of trafficking are important for practitioners caring for patients from the GMR.

From Prevention through to Therapy: Supporting Evidence‐Informed Practice across the Spectrum of Child Maltreatment

From Prevention through to Therapy: Supporting Evidence‐Informed Practice across the Spectrum of Child Maltreatment

Institutions, Extreme Weather, and Urbanization in the Greater Mekong Region

Climate change threatens many developing countries with more frequent and intense extreme weather events. Researchers, however, have not comprehensively examined how extreme weather influences urbanization and sustainable development. Based on the spatial estimates of precipitation, tropical cyclones, and temperature for the period of 2000 to 2010, we establish an eleven-year climatological record and calculate anomalies at the county and district level in the Greater Mekong Region (GMR). Combining this with urbanization data from the World Bank, we relate weather patterns to growth rates in urban population and urban land use and find that the above-average rainfall in the wet season along with more frequent cold waves and tropical cyclones tend to retard urban development. In contrast, crop failures caused by increasingly severe droughts during the dry season and heat waves accelerate rural–urban migration and the agglomeration of urban poverty. By identifying institutionally varying effects, we further find that nonsocialist countries have additional sensitivity to most weather extremes than more centralized socialist countries, which have stronger ability to mobilize resources for disaster management and relief. Our study contributes to the understanding of effects of weather shocks on socioeconomic outcomes in societies rapidly integrating with the global economy.

A new genus of praying mantis, Chlorocalis n. gen., with two new species from the Greater Mekong region (Mantodea: Mantidae)

SummaryA new genus of praying mantis is described, Chlorocalis n. gen., with two species, C. maternaschulzei n. sp. and C. prasina n. sp. from the Greater Mekong Region. Chlorocalis is placed in Mantidae and can be immediately recognized by the presence of dark brown (male) or yellow-whitish (female) oblique stripes on the forewings, a large conical bulge on the clypeus, two large conical bulges on either side of the inferior margin of the lower frons, and the male genitalia with two distal processes on the ventral phallomere. Chlorocalis maternaschulzei is a widespread lowland species with records as west as Nakhon Ratchasima Province, Thailand, and as east as mount Núi Chúa in southern Central Vietnam. We consider this species to be of Least Concern. In contrast, C. prasina is a narrow-range mountain endemic of the Vietnamese Central Highlands in the Annamite range and is assessed by us to be Vulnerable. The new findings demonstrate the still very poor knowledge on praying mantis species diversity in South-East Asia and the urgency to resolve this taxonomic deficiency in the face of biodiversity loss.

Plasmodium falciparum artemisinin resistance monitoring in Sabah, Malaysia: in vivo therapeutic efficacy and kelch13 molecular marker surveillance

BackgroundSpreading Plasmodium falciparum artemisinin drug resistance threatens global malaria public health gains. Limited data exist to define the extent of P. falciparum artemisinin resistance southeast of the Greater Mekong region in Malaysia.MethodsA clinical efficacy study of oral artesunate (total target dose 12 mg/kg) daily for 3 days was conducted in patients with uncomplicated falciparum malaria and a parasite count < 100,000/µL admitted to 3 adjacent district hospitals in Sabah, East Malaysia. On day 3 and 4 all patients were administered split dose mefloquine (total dose 25 mg/kg) and followed for 28 days. Twenty-one kelch13 polymorphisms associated with P. falciparum artemisinin resistance were also evaluated in P. falciparum isolates collected from patients presenting to health facilities predominantly within the tertiary referral area of western Sabah between 2012 and 2016.ResultsIn total, 49 patients were enrolled and treated with oral artesunate. 90% (44/49) of patients had cleared their parasitaemia by 48 h and 100% (49/49) within 72 h. The geometric mean parasite count at presentation was 9463/µL (95% CI 6757–13,254), with a median time to 50% parasite clearance of 4.3 h (IQR 2.0–8.4). There were 3/45 (7%) patients with a parasite clearance slope half-life of ≥ 5 h. All 278 P. falciparum isolates evaluated were wild-type for kelch13 markers.ConclusionThere is no suspected or confirmed evidence of endemic artemisinin-resistant P. falciparum in this pre-elimination setting in Sabah, Malaysia. Current guidelines recommending first-line treatment with ACT remain appropriate for uncomplicated malaria in Sabah, Malaysia. Ongoing surveillance is needed southeast of the Greater Mekong sub-region.

Population pharmacokinetic and pharmacodynamic properties of artesunate in patients with artemisinin sensitive and resistant infections in Southern Myanmar

BackgroundArtemisinins are the most effective anti-malarial drugs for uncomplicated and severe Plasmodium falciparum malaria. However, widespread artemisinin resistance in the Greater Mekong Region of Southeast Asia is threatening the possibility to control and eliminate malaria. This work aimed to evaluate the pharmacokinetic and pharmacodynamic properties of artesunate and its active metabolite, dihydroartemisinin, in patients with sensitive and resistant falciparum infections in Southern Myanmar. In addition, a simple nomogram previously developed to identify artemisinin resistant malaria infections was evaluated.MethodsFifty-three (n = 53) patients were recruited and received daily oral artesunate monotherapy (4 mg/kg) for 7 days. Frequent artesunate and dihydroartemisinin plasma concentration measurements and parasite microscopy counts were obtained and evaluated using nonlinear mixed-effects modelling.ResultsThe absorption of artesunate was best characterized by a transit-compartment (n = 3) model, followed by one-compartment disposition models for artesunate and dihydroartemisinin. The drug-dependent parasite killing effect of dihydroartemisinin was described using an Emax function, with a mixture model discriminating between artemisinin sensitive and resistant parasites. Overall, 56% of the studied population was predicted to have resistant malaria infections. Application of the proposed nomogram to identify artemisinin-resistant malaria infections demonstrated an overall sensitivity of 90% compared to 55% with the traditional day-3 positivity test.ConclusionThe pharmacokinetic-pharmacodynamic properties of artesunate and dihydroartemisinin were well-characterized with a mixture model to differentiate between drug sensitive and resistant infections in these patients. More than half of all patients recruited in this study had artemisinin-resistant infections. The relatively high sensitivity of the proposed nomogram highlights its potential clinical usefulness.

Induction of high tolerance to artemisinin by sub-lethal administration: A new in vitro model of P. falciparum.

Artemisinin resistance is a major threat to malaria control efforts. Resistance is characterized by an increase in the Plasmodium falciparum parasite clearance half-life following treatment with artemisinin-based combination therapies (ACTs) and an increase in the percentage of surviving parasites. The remarkably short blood half-life of artemisinin derivatives may contribute to drug-resistance, possibly through factors including sub-lethal plasma concentrations and inadequate exposure. Here we selected for a new strain of artemisinin resistant parasites, termed the artemisinin resistant strain 1 (ARS1), by treating P. falciparum Palo Alto (PA) cultures with sub-lethal concentrations of dihydroartemisinin (DHA). The resistance phenotype was maintained for over 1 year through monthly maintenance treatments with low doses of 2.5 nM DHA. There was a moderate increase in the DHA IC50 in ARS1 when compared with parental strain PA after 72 h of drug exposure (from 0.68 nM to 2 nM DHA). In addition, ARS1 survived treatment physiologically relevant DHA concentrations (700 nM) observed in patients. Furthermore, we confirmed a lack of cross-resistance against a panel of antimalarials commonly used as partner drugs in ACTs. Finally, ARS1 did not contain Pfk13 propeller domain mutations associated with ART resistance in the Greater Mekong Region. With a stable growth rate, ARS1 represents a valuable tool for the development of new antimalarial compounds and studies to further elucidate the mechanisms of ART resistance.

Estimation on local transmission of malaria by serological approach under low transmission setting in Myanmar

BackgroundAs the prevalence of the malaria has been decreasing in many endemic countries including Myanmar, malaria elimination in Greater Mekong Region was targeted not later than 2030. The relevance of molecular and serological tools to identify residual transmission remains to be established in this setting.MethodsOne-year cohort study was conducted and sera samples were collected in every 3 months with active and passive case detection for clinical malaria episodes by RDT, microscopy and molecular method. The sera were used to detect the malaria antibody against PfMSP1-19, PvAMA1, PvDBPII and PvMSP1-19 by protein microarray.ResultsAmong the recruited 1182 participants, there was no RDT positive case for malaria infection although two vivax infections were detected by microscopy in initial collection. Molecular methods detected the asymptomatic cases of 28/1182 (2.37%) in first, 5/894 (0.42%) in second, 12/944 (1.02%) in third, 6/889 (0.51%) in fourth collection, respectively. Seropositivity rates against the PfMSP1-19, PvMSP1-19, PvAMA1 and PvDBPII were 73/270 (27.0%), 85/270 (31.5%), 65/270 (24.1%) and 160/270 (59.3%), respectively. PfMSP1-19 and PvMSP1-19 showed high and stable antigenicity in acute and subacute samples but declining in 1-year history samples. No cross reactivity of PfMSP1-19 and PvMSP1-19 between the two species and higher seropositivity among the asymptomatic carriers were observed. Mapping data indicated serological surveillance can detect the geographical pattern of malaria infection under low transmission setting.ConclusionsThese findings support that PfMSP1-19 and PvMSP1-19 are suggested for serosurveillance of the malaria especially in low transmission setting for further necessary actions have to be carried out to eliminate the malaria.

Molecular analysis demonstrates high prevalence of chloroquine resistance but no evidence of artemisinin resistance in Plasmodium falciparum in the Chittagong Hill Tracts of Bangladesh

BackgroundArtemisinin resistance is present in the Greater Mekong region and poses a significant threat for current anti-malarial treatment guidelines in Bangladesh. The aim of this molecular study was to assess the current status of drug resistance in the Chittagong Hill Tracts of Bangladesh near the Myanmar border.MethodsSamples were obtained from patients enrolled into a Clinical Trial (NCT02389374) conducted in Alikadam, Bandarban between August 2014 and January 2015. Plasmodium falciparum infections were confirmed by PCR and all P. falciparum positive isolates genotyped for the pfcrt K76T and pfmdr1 N86Y markers. The propeller region of the kelch 13 (k13) gene was sequenced from isolates from patients with delayed parasite clearance.ResultsIn total, 130 P. falciparum isolates were available for analysis. The pfcrt mutation K76T, associated with chloroquine resistance was found in 81.5% (106/130) of cases and the pfmdr1 mutation N86Y in 13.9% (18/130) cases. No single nucleotide polymorphisms were observed in the k13 propeller region.ConclusionThis study provides molecular evidence for the ongoing presence of chloroquine resistant P. falciparum in Bangladesh, but no evidence of mutations in the k13 propeller domain associated with artemisinin resistance. Monitoring for artemisinin susceptibility in Bangladesh is needed to ensure early detection and containment emerging anti-malarial resistance.